Potassium arsenate
Encyclopedia
Potassium arsenate is the chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

  KH2AsO4. Other salts are also called potassium arsenate, including K2HAsO4 and K3AsO4. Each of these species is derived from arsenic acid
Arsenic acid
Arsenic acid is the chemical compound with the formula H3AsO4. More descriptively written as AsO3, this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic acid as such has not been isolated, but only found in solution where it...

:
H3AsO4 + KOH → KH2AsO4 + H2O
KH2AsO4 + KOH → K2HAsO4 + H2O
K2HAsO4 + KOH → K3AsO4 + H2O

These species are closely related to the corresponding potassium phosphate
Potassium phosphate
Potassium phosphate is a generic term for the salts of potassium and phosphate ions including:* Monopotassium phosphate * Dipotassium phosphate * Tripotassium phosphate...

s. The anions H2AsO4, HAsO42, and AsO43 feature tetrahedral AsO4 with two, one, or no H atoms attached to the oxygen atom(s), respectively.

Although this and related arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

salts have been prescribed for health purposes, such compounds are highly toxic.
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